ClangImporter: Add support for __attribute__((availability(..., replacement="")))

We map clang::AvailabilityAttr::getReplacement() to
swift::AvailableAttr::Rename, transforming the replacement
name using by looking up the named Clang replacement, and
importing its name.

Fixes <rdar://problem/26301742>.

Author: slavapestov

lib/ClangImporter/ClangImporter.cpp

@@ -1928,6 +1928,7 @@ printFullContextPrefix(ClangImporter::Implementation::ImportedName name,
 }
 
 void ClangImporter::Implementation::printSwiftName(ImportedName name,
+                                                   bool fullyQualified,
                                                    llvm::raw_ostream &os) {
   // Property accessors.
   bool isGetter = false;
@@ -1949,9 +1950,7 @@ void ClangImporter::Implementation::printSwiftName(ImportedName name,
     break;
   }
 
-  // If we're importing a global as a member, we need to provide the
-  // effective context.
-  if (name.ImportAsMember)
+  if (fullyQualified)
     printFullContextPrefix(name, os, *this);
 
   // Base name.

lib/ClangImporter/ImportDecl.cpp

@@ -1292,7 +1292,12 @@ namespace {
       {
         // Render a swift_name string.
         llvm::raw_svector_ostream os(renamed);
-        Impl.printSwiftName(swift3Name, os);
+
+        // If we're importing a global as a member, we need to provide the
+        // effective context.
+        Impl.printSwiftName(swift3Name,
+                            /*fullyQualified=*/swift3Name.ImportAsMember,
+                            os);
       }
 
       auto attr = AvailableAttr::createUnconditional(
@@ -6093,6 +6098,38 @@ clang::SwiftNewtypeAttr *ClangImporter::Implementation::getSwiftNewtypeAttr(
   return decl->getAttr<clang::SwiftNewtypeAttr>();
 }
 
+StringRef ClangImporter::Implementation::
+getSwiftNameFromClangName(StringRef replacement) {
+  auto &clangSema = getClangSema();
+
+  clang::IdentifierInfo *identifier =
+      &clangSema.getASTContext().Idents.get(replacement);
+  clang::LookupResult lookupResult(clangSema, identifier,
+                                   clang::SourceLocation(),
+                                   clang::Sema::LookupOrdinaryName);
+  if (!clangSema.LookupName(lookupResult, nullptr))
+    return "";
+
+  auto clangDecl = lookupResult.getAsSingle<clang::NamedDecl>();
+  if (!clangDecl)
+    return "";
+
+  auto importedName = importFullName(clangDecl, None, &clangSema);
+  if (!importedName)
+    return "";
+
+  llvm::SmallString<64> renamed;
+  {
+    // Render a swift_name string.
+    llvm::raw_svector_ostream os(renamed);
+    printSwiftName(importedName,
+                   /*fullyQualified=*/true,
+                   os);
+  }
+
+  return SwiftContext.AllocateCopy(StringRef(renamed));
+}
+
 /// Import Clang attributes as Swift attributes.
 void ClangImporter::Implementation::importAttributes(
     const clang::NamedDecl *ClangDecl,
@@ -6111,7 +6148,7 @@ void ClangImporter::Implementation::importAttributes(
   for (clang::NamedDecl::attr_iterator AI = ClangDecl->attr_begin(),
        AE = ClangDecl->attr_end(); AI != AE; ++AI) {
     //
-    // __attribute__((unavailable)
+    // __attribute__((unavailable))
     //
     // Mapping: @available(*,unavailable)
     //
@@ -6157,8 +6194,13 @@ void ClangImporter::Implementation::importAttributes(
 
       // Is this our special "availability(swift, unavailable)" attribute?
       if (Platform == "swift") {
+        auto replacement = avail->getReplacement();
+        StringRef swiftReplacement = "";
+        if (!replacement.empty())
+          swiftReplacement = getSwiftNameFromClangName(replacement);
+
         auto attr = AvailableAttr::createUnconditional(
-            C, avail->getMessage(), /*renamed*/"",
+            C, avail->getMessage(), swiftReplacement,
             UnconditionalAvailabilityKind::UnavailableInSwift);
         MappedDecl->getAttrs().add(attr);
         AnyUnavailable = true;
@@ -6211,12 +6253,17 @@ void ClangImporter::Implementation::importAttributes(
 
       const auto &obsoleted = avail->getObsoleted();
       const auto &introduced = avail->getIntroduced();
+      const auto &replacement = avail->getReplacement();
+
+      StringRef swiftReplacement = "";
+      if (!replacement.empty())
+        swiftReplacement = getSwiftNameFromClangName(replacement);
 
       auto AvAttr = new (C) AvailableAttr(SourceLoc(), SourceRange(),
-                                             platformK.getValue(),
-                                             message, /*rename*/StringRef(),
-                                             introduced, deprecated, obsoleted,
-                                             Unconditional, /*implicit=*/false);
+                                          platformK.getValue(),
+                                          message, swiftReplacement,
+                                          introduced, deprecated, obsoleted,
+                                          Unconditional, /*implicit=*/false);
 
       MappedDecl->getAttrs().add(AvAttr);
     }

lib/ClangImporter/ImporterImpl.h

@@ -935,8 +935,9 @@ class LLVM_LIBRARY_VISIBILITY ClangImporter::Implementation
                              const clang::MacroInfo *macro,
                              clang::ASTContext &clangCtx);
 
-  /// Print an imported name as a string suitable for the swift_name attribute.
-  void printSwiftName(ImportedName, llvm::raw_ostream &os);
+  /// Print an imported name as a string suitable for the swift_name attribute,
+  /// or the 'Rename' field of AvailableAttr.
+  void printSwiftName(ImportedName, bool fullyQualified, llvm::raw_ostream &os);
 
   /// Retrieve the property type as determined by the given accessor.
   static clang::QualType
@@ -982,6 +983,9 @@ class LLVM_LIBRARY_VISIBILITY ClangImporter::Implementation
       const clang::TypedefNameDecl *decl,
       bool useSwift2Name);
 
+  /// Map a Clang identifier name to its imported Swift equivalent.
+  StringRef getSwiftNameFromClangName(StringRef name);
+
   /// Import attributes from the given Clang declaration to its Swift
   /// equivalent.
   ///

test/ClangModules/availability.swift

@@ -115,3 +115,8 @@ func testImportAsMember() {
   _ = CGColorCreateGenericGray(0.5, 1.0) // expected-error {{'CGColorCreateGenericGray' has been replaced by 'CGColor.init(gray:alpha:)'}} {{7-31=CGColor}} {{32-32=gray: }} {{37-37=alpha: }}
   _ = CGColor(gray: 0.5, alpha: 1.0)
 }
+
+func testUnavailableRenamedEnum() {
+  _ = NSClothingStyle.hipster
+  _ = NSClothingStyleOfficeCasual // expected-error{{'NSClothingStyleOfficeCasual' has been renamed to 'NSClothingStyle.semiFormal'}} {{7-34=NSClothingStyle.semiFormal}}
+}

test/Inputs/clang-importer-sdk/usr/include/Foundation.h

@@ -1021,3 +1021,11 @@ extern NSString *NSHTTPRequestKey;
 
 #define NSTimeIntervalSince1970 978307200.0
 #define NS_DO_SOMETHING 17
+
+typedef NS_ENUM(NSUInteger, NSClothingStyle) {
+  NSClothingStyleFormal = 0,
+  NSClothingStyleSemiFormal,
+  NSClothingStyleHipster,
+  NSClothingStyleHippie
+};
+static const NSClothingStyle NSClothingStyleOfficeCasual __attribute__((availability(swift,unavailable,replacement="NSClothingStyleSemiFormal"))) = NSClothingStyleSemiFormal;